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function

...reach their final size toward age 20. The sinuses are located in four different skull bones—the maxilla, the frontal, the ethmoid, and the sphenoid bones. Correspondingly, they are called the
maxillary sinus, which is the largest cavity; the frontal sinus; the ethmoid sinuses; and the sphenoid sinus, which is located in the upper posterior wall of the nasal cavity. The sinuses have two...

structure

The
maxillary sinuses are not only the largest of the air sinuses but also the first to appear, being present in the fourth month of intrauterine life. Each is a pyramidal space, its roof formed by the floor of the eye socket, and its floor by the palate and teeth-bearing bone. The roots of the upper-jaw teeth may project through the floor into the sinus cavity or may be so closely related to...